Copasetic Flow

It seems like some of the topics for the US extra class exam would be better served by help videos instead of long detailed written help pages. So, here's the first video help topic for Copasetic Flows free ham radio practice exams. It covers direct digital synthesizers. Please let me know what you think and what could be improved or changed. Video seems to have been in the air for ham radio this weekend. Here are some of my favorite ham radio blogs that also posted videos this weekend: SolderSmoke: WSPR the Movie G4ILO: Installing APRSISCE/32 W2AEW's Dorkage Blog: Delayed Timebase operation example and GOKYA: GB0CMS, Caister Marconi Station

This was a walk near Sound Beach, NY The Waves: The walk:

Lots of cool stuff! This lecture has nice clean explanations of: 1. How a heat engine diagram is used 2. What adiabiatic means, (doesn’t exchange heat outside the system) 3. Why work examples are inexact, (they’re path dependent) 4. van der Waals equation of state NOTES: Adiabatic: No transfer of heat between the system and the outside world. Can be reversible and not. Isobaric: constant pressure Isothermal: constant temperature triple point of water is used as a reference point for the Kelvin scale because it is the same everywhere. Ideal gas law only holds for a very small range. 21:00 van der Waals equation of state derivation of van der Waals, b is the volume consumed by the hard sphere molecules. a is the attractive force that slightly reduces pressure. a is divided by the molar volume squared because it is more likely to affect things in smaller volumes and less likely in larger volumes. 31:00 Convention in the definition of work. The environment compressing the gas is...

iHAB-4 a high altitude baloon complete with qrp beacon and student science exerpiments will launch this morning! We helped chase iHAB-2 back in October and had a great time! You can read more about the fb work by W0OTM and team at the iHAB-4 web site . The posting to GQRP announcing the launch is copied below: The Iowa High Altitude Balloon project is making it's 4th launch tomorrow morning at 10Am Central, 1500z, from Cedar Rapids, Iowa. A major milestone is that science student's cannister experiments will be carried aloft and analyzed upon recovering the payload. One of the goals of this launch is to do a remotely triggered cut down at 75,000 feet, or over the Mississippi River, whichever comes first. The tether between the payload and the balloon will be severed from a ground command. A test of the cutdown circuit at low temperature can be viewed here http://www.youtube.com/watch?v=S4voKhzUflM As on the last flight, a 2M simplex repeater will be operatiing on 147.500 PL T...

Still watching MIT Freshhman EM lectures in preparation for quals. Notes and time stamps follow the video. Biot Savart C = mu0/4pi = 10 ^ -7 9:40 Magnetic field from current loop 15:00 Dual of current loop magnetic field and electric dipole electric field Magnetic flux through a closed surface is always 0. 37:30 Leiden jar disassemble and discharge example Demonstrates corona discharge from metal to the insulating glass Removing charge from the insulating glass is difficult

In getting ready for quals next January, I found out that MIT provides several of their courses online. I watched the freshman physics lecture on magnetism today and it's awesome! There are demos of the forces created on wires by magnetic fields, (car batteries are apparently the key to getting this demo right), as well as simple electric motor demos. There are also several everyday applications that make the Lorentz force equation immediately applicable. The video is embedded after the notes. Notes: Force on a wire due to a B field

I mentioned before that I was doing some research on the history of SSB in amateur radio and promised my reading list. Here it is. ARRL " Amateur Radio and the Rise of SSB " [pdf] GE Sideband Handbook Chapter 2 detailing the SSB Junior among other things [pdf] GE Ham News detailing the "Signal Slicer" SSB receiver from July 1951 [pdf] How Donald Noorgard's SSB Junior inspired Wes Schum's Central Electronics Model 10A . Historical reference on the RCA transmitting station at Rocky Point, NY, site of the first transatlantic SSB transmission Rocky Point Historical Society essay on the RCA transmitting station Wikipedia entry for Rocky Point, NY mentioning the RCA transmitter site Modern pictures of what is left of the RCA transmitting site at Rocky Point, NY WB9IPA QRP SSB project with its own great reading list